In many cities the utilities are located beneath the surface of the earth, usually beneath the surface of the streets. These utilities are placed in tunnels or conduits. In the older cities, such as New York City, these utilities have been located in conduits for years or even decades. Over time the conduits which carry utilities may wear out and break. Further, electrical lines may simply be used beyond their use life as higher electrical loads are placed upon the lines. A serious problem is the failure of electrical transmission lines. These failures usually result in fires which must be quickly extinguished to prevent damage to the surrounding infrastructure.
While it is desirable to replace very old utilities in conduits and tunnels, it is not always practical. Due to financial restraints and other limitations, most of these electrical transmission lines have not been replaced. Unfortunately, failure of older electrical transmission lines can result in an electrical fire. These fires are commonly discovered when smoke is seen arising from manhole covers in the streets and sidewalks. It has been estimated by Consolidated Edison that there are approximately 40 electrical fires per day under the streets of New York City.
The cost of repairing and replacing the electrical transmission lines damaged by these fires is approximately $100,000.00 per linear foot of transmission line. Therefore, it is imperative that these fires be extinguished as quickly as possible. Inspection of lines can help pinpoint potential trouble areas. Unfortunately, inspection of the lines can trigger a fire. For instance, the opening of a manhole cover can provide the oxygen needed to support a fire. Similarly, a lineman performing an inspection may disturb a conduit resulting in arcing of electric lines, possibly triggering a fire.
Normally a lineman inspecting a potential problem area occurs while electrical power is still flowing through the lines. The inspection takes place within the manhole wherein a lineman inserts himself into the manhole. Typically a ladder is placed through the manhole and the lineman climbs down the ladder to permit inspection from within. Unfortunately the lineman can trigger a fire, or simply be in the wrong place at the wrong time. There have been many instances where a fire begins while the lineman is on the ladder. For instance, a fire may be smoldering as evidence by smoking coming out of the manhole. A lineman or fireman may then enter the manhole and, without notice, the smoldering may burst into an all encompassing fire. In many such instances, the individual who climbed into the manhole is now at risk of injury or death.
Another area of concern is the use of ladders for extracting of people from burning buildings. Firemen do not hesitate to lean a ladder against a building to reach the lower floors in an effort to fight fires or extract survivors. Unfortunately such a situation cannot predict if a fire will erupt from a lower floor and engulf the firefighter while he/she is on the ladder. While the firefighter is likely prepared for flash fire and is appropriately dressed, any survivor that they are pulling down the ladder will not be dressed should a fire approach the ladder area.
Thus, what is needed is an improved ladder that provides fire protection to the individual that climbs down the manhole for servicing of the electrical grid beneath the ground, or otherwise uses a ladder in an area where a fire may occur.
U.S. Pat. No. 6,834,728 discloses a system for extinguishing a fire in a tunnel. The system includes a conduit for delivering a fire extinguishing liquid and a trough extending parallel to the conduit for receiving liquid from the conduit. A carriage is arranged to move on a track which includes an upper edge of the trough. The carriage carries a pump having a nozzle, a video camera, and an inlet; each of which can be controlled robotically from a remote control station. The inlet is deployed in the trough to draw liquid from the trough.
U.S. Pat. No. 7,096,965 discloses a method of proportioning a foam concentrate into a non-flammable liquid to form a foam concentrate/liquid mixture and create a flowing stream of the foam concentrate/liquid mixture. Nitrogen is introduced into the stream of the foam/liquid mixture to initiate the formation of a nitrogen expanded foam fire suppressant. The flowing stream carrying the nitrogen expanded foam is dispensed, which completes the full expansion of the nitrogen expanded foam fire suppressant, into the confined area involved in the fire, thereby smothering the fire and substantially closing off contact between combustible material involved in the fire and the atmosphere. The apparatus of this invention is adapted for expanding and dispensing foam and includes a housing defining an interior through which extends a discharge line. The ends of the housing are closed about the ends of the discharge line, and the ends of the discharge line extend beyond the ends of the housing to define a connector at one end for receiving a stream of foam concentrate/liquid and at the opposite end to define the foam dispensing end of the apparatus. A portion of the discharge line in the housing defines an educator for the introduction of expanded gas into the stream of foam concentrate/liquid flowing through the discharge line.
U.S. Pat. No. 7,104,336 discloses a method and apparatus for proportioning a foam concentrate into a non-flammable liquid to form a foam concentrate/liquid mixture and create a flowing stream of the foam concentrate/liquid mixture similar to the method and apparatus of U.S. Pat. No. 7,096,965.
U.S. Pat. No. 7,124,834 discloses a method for extinguishing a fire in a space such as a tunnel. The method includes spraying a fire extinguishing medium into the space by spray heads. In a first stage of the method, the flow and temperature of the hot gases produced by the fire are influenced by spraying an extinguishing medium into the space, especially by creating in the space at least one curtain of extinguishing medium. At least some spray heads in the space are pre-activated into a state of readiness. In a second stage of the method, at least one spraying head is activated to produce a spray of extinguishing medium.
U.S. patent application Ser. No. 11/680,803 is entitled “Process for Fire Prevention and Extinguishing”, the contents of which are incorporated herein by reference. In this application, a process for retarding or extinguishing conflagrations using a super absorbent polymer in water is disclosed. The reaction of the water with the polymer creates a gel-like substance with a viscosity that allows the mixture to be readily pumped through a standardized 2.5 gallon water based fire extinguisher, yet viscous enough to cover vertical and horizontal surfaces to act as a barrier to prevent fire from damaging such structures, minimizing the manpower needed to continuously soak these structures.
U.S. Pat. No. 7,169,843 discloses absorptive, cross-linked polymers which are based on partly neutralized, monoethylenically unsaturated monomers carrying acid groups, and with improved properties, which has a high gel bed permeability and high centrifuge retention capacity.
U.S. Pat. No. 5,989,446 discloses a water additive for use in fire extinguishing and prevention. The additive comprises a cross-linked water-swellable polymer in a water/oil emulsion. The polymer particles are dispersed in an oil emulsion wherein the polymer particles are contained within discrete water “droplets” within the oil. With the help of an emulsifier, the water “droplets” are dispersed relatively evenly throughout the water/oil emulsion. This allows the additive to be introduced to the water supply in a liquid form, such that it can be easily educted with standard firefighting equipment.
U.S. Pat. No. 5,190,110 discloses the fighting of fires or protection of objects from fire by applying water which comprises dispersing in the water particles of a cross-linked, water-insoluble, but highly water-swellable, acrylic acid derivative polymer in an amount insufficient to bring the viscosity above 100 mPa's. Advantageously, the particles are present in an amount such that, after swelling, the swollen particles hold 60 to 70% by weight of the total water; the polymer being a copolymer of an acrylic acid, the water containing silicic acid and/or a silicate as well as sodium, potassium or ammonium ions. The water is freely pumpable, but the swollen particles adhere to surfaces they contact rather than running off rapidly.
U.S. Pat. No. 5,849,210 discloses a method of preventing or retarding a combustible object from burning including the steps of mixing water with a super absorbent polymer (“SAP”) to form one at least partially hydrated SAP, and applying the at least partially hydrated SAP to the combustible object, before or after combustion. In another embodiment, an article of manufacture includes a SAP that is prehydrated and is useful for preventing a combustible object from burning, or preventing penetration of extreme heat or fire to a firefighter or other animal.
U.S. Pat. No. 6,372,842 discloses methods of using an aqueous composition or dispersion containing a water-soluble or water-dispersible synthetic polymer, and compositions formed thereof. The aqueous composition or dispersion is added to agricultural spray, ink, deicing, latex paint, cleaner and fire-extinguishing chemical compositions, water-based hydraulic compositions, dust control compositions and so on, to impart properties including, but not limited to, aerosol control, shear stability, transfer efficiency, oil/water reduction, emollient performance, lubricity, thickening, and anti-wear capability, to the resultant composition formed thereof.
U.S. Pat. No. 5,087,513 discloses polybenzimidazole polymer/superabsorbent polymer particles. These articles are prepared by either mixing the super absorbent polymer particulates with the polybenzimidazole polymer solution during the formation of the polybenzimidazole article, or forming a composite of a polybenzimidazole film or fiber material layer with a super absorbent polymer particulate containing layer. These polybenzimidazole products absorb large amounts of fluid while retaining the flame retardancy and chemical unreactivity of conventional polybenzimidazole materials.
U.S. Pat. No. 4,978,460 discloses a particulate additive for water for fire fighting containing a strongly swelling water-insoluble high molecular weight polymer as gelatinizing agent, which comprises a water-soluble release agent which causes the particles of said gelatinizing agent not to swell, the particles of the gelatinizing agent being encased or dispersed in the release agent. Suitable release agents include polyethylene glycol, sugars, mannitol, etc. The gelatinizing agent may be a moderately cross-linked water-insoluble acrylic or methacrylic acid copolymer.
U.S. Pat. No. 5,519,088 discloses an aqueous gel comprising a polymer of (meth)acrylamide or particular (meth)acrylamide derivative(s), particulate metal oxide(s) and an aqueous medium, a process for producing said gel, and products utilizing said gel. This aqueous gel can be produced so as to have transparency, be highly elastic and fire resistant and can prevent the spreading of flames. The aqueous gel when produced transparent, becomes cloudy when heated or cooled and is useful for the shielding of heat rays or cold radiation.